Variably releasable ski bindings



p 1 1970 R. L. MYERSON 3,528,673

VARIABLY RELEASABLE SKI BINDINGS Filed Aug. 8, 1966 2 Sheets-Sheet 2 lOOq PERCENT OF INSTANTANEOUS RELEASE LOAD 5O TIME F I G 5 ENVENTOR.

RICHARD L. MYERSON BY ATTORINEYS 3,528,673 VARIABLY RELEASABLE SKI BINDINGS Richard L. Myerson, 14 Oak Hill St.,

Newton Centre, Mass. 02159 Filed Aug. 8, 1966, Ser. No. 571,090 Int. Cl. A63c 9/08 US. Cl. 280-11.35 12 Claims ABSTRACT OF THE DISCLOSURE Ski bindings are made releasable to permit the disengagement of skis when strains and loads encountered in skiing become excessive. For commonly employed bindings, the load at which release takes place is adjustable, but once set, remains fixed. Consequently, skiers typically set their bindings to release for some average load. As a result, when there is a departure from average conditions, the bindings may fail to release, or may release prematurely.

For example, in the case of high speed skiing and racing, the release point is set at a relatively high level to prevent premature release while negotiating turns. As a consequence, the skis Will not disengage for many hazardous low speed conditions. Conversely, a low level release point, set in anticipation of moderate speeds, creates the hazard of premature release when skiing speed increases.

Accordingly, it is an object of the invention to provide ski bindings which are releasable for various unsafe operating conditions regardless of their associated load levels.

It is a related object of the invention to provide bindings which are suitable for high speed skiing but, are, nevertheless, releasable for dangerous low speed conditions. Conversely, it is also an object of the invention to provide bindings which are releasable for dangerous low speed conditions but also are suitable for high speed maneuvermg.

In accomplishing the foregoing and related objects, the invention provides variable response ski bindings that are releasable in accordance with both the magnitude and duration of each applied load. Thus a light load applied for a prolonged time will produce a release effect that is similar to that of a heavy load applied for a shorter time.

A variable response binding in accordance with the invention is particularly suitable for use in skiing because of the different time factors commonly encountered. In the case of a spill in high speed skiing, it takes only a short time for the skier to reach a position where the binding should release if hazard is to be avoided. Contrawise, it takes a longer time before there is hazard in a spill at a low speed.

A variable response binding in accordance with the invention includes a dampening assembly which is attached to a ski by a holder to make contact with a ski boot. The dampening assembly is formed by a plunger, which, by having an orifice, is able to move through a fluid bath. The flow of fluid through the orifice dampens the motion of the plunger, as it moves through the bath. Such a dampening assembly is commonly called a dash-pot.

By contrast with exclusively spring-loaded bindings, a dash-pot binding does not react immediately to an applied force because fluid flow through the orifice is restricted. Hence the displacement of the dash-pot plunger depends upon both the magnitude and the duration of the applied load.

ice

In order to permit an immediate response as well, the load applied to the dampening assembly may be extended to a spring assembly which functions in conventional fashion.

Other aspects of the invention will become apparent after considering an illustrative embodiment, taken in conjunction with the drawings which:

FIG. 1 is a partial view of a ski with variable load bindings attached in accordance with the invention;

FIG. 2 is a cross-sectional view of a variable load binding for the ski of FIG. 1;

FIG. 3 is a partial cross-sectiona1 view of an alternative dampening assembly for the binding of FIG. 2;

FIG. 4 is a schematic representation of members of the binding of FIG. 2; and

FIG. 5 is a graph illustrating the relationship between load and release time for representative bindings in accordance with the invention.

Turning to the drawings, FIG. 1 shows a ski boot 10 attached to a ski 11 using a releasable toe binding 20 and a releasable heel binding 20'. Both the toe and heel bindings 20 and 20' are housed by metal frames 21 and 21, which are desirably bolted to the ski 11. The bindings 20 and 20 include nose pieces 22 and 22', dash-pots 23 and 23' and assemblies 24 and 24'. The assemblies 24 and 24' are advantageously spring loaded. Details of the toe binding 20, including a spring loaded assembly 24, are set forth in FIG. 2.

Continuing in FIG. 1, the nose piece 22 of the toe binding 20 engages a toe plate 12 which is attached to the toe portion of the boot 10 on its underside. A similar nose piece 22' of the heel binding 20 engages a heel plate 13. Unlike the toe plate 12, the heel plate 13 has a spherical indent in its rear portionywhich is engaged by a mating protuberance of the nose piece 22'.

When the forward thrust of the boot 10 becomes excessive, for a sufficient duration of time, the nose piece 22 slides forward in its frame 21 and allows the boot to become disengaged from the heel binding element 20'. Conversely, if there is excessive backward thrust, the nose piece 22' slides to the rear in its frame 21 and releases the boot from the toe binding element 20. Because of the spherical indent in the rear portion of the heel plate 13 a side thrust from either direction will also cause the nose piece 22' to slide to the rear and release the boot 10.

Referring to FIG. 2, the constituents of the assembly 24 and the dash-pot 23 for the binding 20 are shown in detail. The dash-pot 23 includes a housing 23-1, which encases an internal spring 23-2 and a piston 23-3. The chamber of the dash-pot is filled with a fluid 23-4, which may be either liquid or gaseous. In the embodiment of FIG. 2, the main constituent of the assembly 24 is a spring member 24-1.

A forward load applied to the nose piece 22 causes a relatively instantaneous compression of the spring 24-1. However, before the internal spring 23-2 can be compressed, the fluid 23-4 must be forced through a small orifice 23-5 in the piston 23-3. If the fluid is gaseous, a smaller orifice is required than if the fluid is liquid. The viscosity of the fluid 23-4 and the size of the orifice 23-5 regulate the rate of compression of the spring 23-2. Thus for short duration loads, there will be virtually no compression of the spring 23-2 and the release point of the binding 20 will be determined by the stiffness of the spring 24-1. If the load is applied for a longer period of time, there will be additional deflection, over and above that associated with the spring 24-1, after the piston 23-3 has pushed the fluid 23-4 through the orifice 23-5 and compressed the spring 23-2.

The assembly 24 may be a rigid member, in place of the spring 24-1, so that the binding becomes essentially a spring 23-2 and a dash-pot 23 in parallel. When the assembly 24 is a rigid member, there will be virtually no deflection at the instant the load is applied. With the passage of time, however, the spring 23-2 compresses until the restoring force is equal to the applied load. Thus a finite amount of time is required before any applied thrust causes a release of the binding. The greater the magnitude of the thrust, the shorter is the release time.

The-binding of FIG. 2 is readily adjusted for a particular high-speed release. For this purpose, a shaft 24-2 inserted through, and supporting the spring 24-1, is threaded over a considerable portion of its length. A nut 24-3 is tightened, compressing the spring 24-1. The head 24-4 of the shaft 24-2 is shaped to be held by a wrench while the nut 24-3 is being tightened. The equilibrium tension exerted by the spring 24-1 tends to hold the nose piece 22 against the frame 21.

In the dash-pot 23, the nose piece 22 is threadably attached to the piston 23-3. Where the fluid 23-4 is a liquid, leakage of the fluid from the chamber of the dash-pot 23 is prevented by a flexible gasket 23-6, which is inserted between the nose piece 22 and the piston 23-3 and secured against the housing 23-1 by a cover 23-7. Alternatively, the seal 23-6 may be an O-ring or other suitable seal for a slidable piston. The seal 23-6 is not needed where the fluid 23-4 is gaseous. The piston 23-3 includes a disc, preferably of metal, which does not extend fully to the walls of the housing 23-1. Overlying the disc and extending to the housing 23-1 is a flanged cup 23-3 of composition material such as rubber. When compressive force is applied by way of the nose piece 22, the flanged cup 23-8 is pushed slidably against the walls of the housing 23-1, forcing fluid through the small orifice 23-5. Conversely, when the load is released, the flanged edges of the cup 23-8 are deflected from the walls of the housing 23-1 and the spring 23-2 brings about a rapid return of the piston 23-3 to its initial position.

Where the fluid 23-4 in the dash-pot 23 is liquid, it is desirably stable at the low temperatures encountered in skiing and exhibits a small change in viscosity with temperature change. Silicone oils have been found to meet these requirements satisfactorily.

The condition of the fluid 23-4 of the dash-pot 23 may be checked by use of a gauge 25 in a test port. With the gauge in place, pressure is applied to the nose piece 22 and there should be an immediate response, which gradually diminishes as fluid flows through the orifice 23-5.

The dash-pot 23 is readily disassembled and the spring 23-2 and the fluid 23-4 readily replaced, depending upon conditions encountered in skiing. The dash-pot 23 may also be readily replaced as a unit with another unit of different characteristics in order to make an accommodation to a change in skiing conditions.

An alternative form of dash-pot assembly 33 is set forth in FIG. 3 showing a portion of the wall of a housing 33-1 and a portion of a piston assembly 33-3. The piston assembly 33-3 has a small clearance between it and the wall of the housing 33-1 to permit the flow of fluid 33-4, as indicated by the arrow. By using different materials for the piston assembly 33-3 and the wall of the housing 33-1, a difference in thermal expansion can be employed to compensate for a viscosity change in the fluid 33-4. Thus if the piston assembly 33-3 were of plastic, with a relatively high coeflicient of expansion, and the housing 33-1 were of metal, with a low coefficient of expansion, the piston assembly 33-3 would contract more than the housing 33-1 with a reduction in temperature, and the opening between the wall of the housing and the piston assembly would become larger. This would at least partially compensate for an increase in the viscosity of the fluid 33-4 with a reduction in temperature.

To provide for a quick return of the piston assembly 33-1 upon release of the pressure that might be exerted during a skiing turn, the dash-pot 33 of FIG. 3 includes a ball-check valve 33-5. When employing a ball-check valve, force in the direction shown by the arrow B will cause the ball 33-5 to close the main aperture 33-6 of the piston assembly 33-3 and flow is confined to the opening between the assembly 33-3 and the wall of the housing 33-1. On the other hand, when the load is removed and a spring (not shown) moves the piston assembly 33-3 in the direction indicated by arrow A, the ball 33-5 is pushed away from the aperture 33-6 and there is a rapid flow of the fluid 33-4. The ball 33-5 is kept in place by bracket members 33-7.

The overall dampening system of a binding constructed in accordance with the invention is represented schematically in FIG. 4. The spring assembly 24 of FIG. 2 is represented by an ideal spring of stiffness K and the dashpot of FIG. 1 is represented by an ideal plunger of viscosity V, in parallel with an ideal spring of stiffness K If a force F is applied to the system of FIG. 4, the linear displacement D of the system is given by Equation 1:

where e is the base of natural logarithms, t is time and the other symbols have been defined previously.

From Equation 1 it is seen that as the time t approaches zero, the displacement D is determined only by the stiffness K of the spring assembly 24 and by the force F. On the other hand, as the time t extends indefinitely, the displacement D will be determined by the force F and the series combination of the stiffness K and K of the springs 24-1 and 23-2 in the spring assembly 24 and the dash-pot 23.

Characteristic curves 41 and 42 for two different sets of adjustments for the binding 20 of FIG. 2 have been plotted in FIG. 5, assuming, in each case, a constant-force release load. Where the load is non-constant, the curves 41 and 42 of FIG. 5 are modified accordingly.

The X-axis coordinate in FIG. 5 is relative time, in terms of an arbitrary time t. The Y-axis coordinate indicates the constant-force release load associated with various load intervals. The desired release load is given in terms of a stated percentage of instantaneous release load, the latter being the constant force required to release the binding in substantially zero time.

Both curves 41 and 42 are derived from Equation 1 and show dampening attributable to the dash-pot assembly 23 of FIG. 2. The first curve 41 is on the basis that the stiffness K of the spring 24-1 of FIG. 2 is twice the stiffness K of the spring 23-2. It is further assumed for curve 41 that the ratio V/K of effective viscosity V associated with the dash-pot 23, as determined principally by the viscosity of the fluid 23-4 and the aperture 23-5, to stiffness K i.e. the time constant of Equation 1, is the same as the arbitrary time t of the abscissal scale in FIG. 5. For these parameters Equation 1 at time t reduces to:

1 0.64 DJ [K1 K2 The second curve 42 is based on a stiffness K equal to the stiffness K and a ratio of viscosity V to stiffness K that is one-third of the arbitrary time t.

The curves 41 and 42 show that the higher the spring constant K ie the stiffer the spring 24-1, the greater is the load required for early release. However, the lower the spring constant K i.e. the softer the spring 23-2, the lower is the release load for later release. The rate of decay of the curves is governed by the time constant V/K of Equation 1. For slow decay, a high viscosity fluid is used; for rapid decay, a low viscosity fluid is used.

In the case where K is replaced by a rigid member, 1/K will become zero and Equation 1 reduces to:

where the symbols are as defined for Equation 1. It is seen from Equation 2 that there is no instantaneous displacement, but that the displacement is a function of force F, the spring constant K viscosity V and time I. In general, for a binding in accordance with the invention which is essentially a dash-pot in parallel with a spring, the release force versus time characteristic has a much larger slope than for a binding in accordance with the invention where a spring is in series with a spring dashpot assembly.

The principle of one spring yielding after a time delay interval because of dampening, either by itself or in combination with a spring that yields virtually instantaneously to a thrust, can be applied to various combinations of springs and dash-pots to produce a variety of displacement versus time characteracteristics.

Further, the techniques illustrated for a toe release binding can be applied directly to a heel release binding, whether in response to a direct force along the main axis of a ski or a twisting force.

Other modifications of the invention will occur to those skilled in the art including different kinds of springs and dampening fluids to achieve a wide range of displacements, both ultimate and instantaneous, and time effects.

I claim:

1. A ski binding comprising means, attachable to a ski for engaging a ski boot, and means, attachable to said ski and contacted by the engaging means, for controlling the displacement of said engaging means in accordance with both the magnitude of thrust applied by said ski boot thereto and the time duration over which said thrust is applied, wherein said means for controlling the displacement comprises first compressible means, and second compressible means for being compressed by said thrust after the compression of said first compressible means is initiated.

2. Apparatus as defined in claim 1 wherein said first compressible means comprises a spring assembly and said second compressible means comprises a dampening assembly which includes an internal spring connected in series with said spring assembly.

3. A pair of apparatuses as defined in claim 1, one of said apparatuses engaging the toe portion of said ski boot and being responsive to a forward thrust thereof, the other of said apparatuses engaging the heel portion of said ski boot and being responsive to a rearward thrust thereof.

4. Apparatus as defined in claim 3, wherein one of said apparatuses is adapted to respond to sideward thrusts of said ski boot.

5. A ski binding comprising means, attachable to a ski for engaging a ski boot, and means, attachable to said ski and contacted by the engaging means, for controlling the displacement of said engaging means in accordance with both the magnitude of thrust applied by said ski boot thereto and the time duration over which said thrust is applied, wherein said means for controlling the displacement comprises a dash-pot and a spring disposed in parallel with said dash-pot, and wherein said dampening is greater in the compressional direction of motion thereby to permit a rapid restoration of said engaging means to its equilibrium condition following the release of thrust by a ski boot.

6. A ski binding comprising means, attachable to a ski for engaging a ski boot, and means, attachable to said ski and contacted by the engaging means, for controlling the displacement of said engaging means in accordance with both the magnitude of thrust applied by said ski boot thereto and the time duration over which said thrust is applied, wherein said means for controlling the displacement comprises a dash-pot and a spring disposed in parallel with said dash-pot, wherein said dash-pot assembly includes a piston movable through a viscous fluid, wherein said piston and housing therefor are of materials which contract differentially with a decrease of temperature in order to compensate for a corresponding increase in the viscosity of said fluid.

7. A ski binding comprising a frame attachable to a ski, a dampening assembly attached to said frame, and constituted of two relatively displaceable members, a spring interconnecting said relatively displaceable members of said dampening assembly, and means attached to said dampening assembly for engaging a ski boot mounted upon said ski comprising a nose piece inserted through an aperture in said frame and protruding therethrough for engagement with said ski boot, said dampening assembly is within said frame extending from one wall thereof to said nose piece, and said spring is within said dampening assembly.

8. A ski binding comprising a frame attachable to a ski, a dampening assembly attached to said frame, and constituted by two realtively displaceable members, a spring interconnecting said relatively displaceable members of said dampening assembly, and means attached to said dampening assembly for engaging a ski boot mounted upon said ski, whereby a thrust applied to the engaging means results in dampened compression of said spring, including a spring assembly interconnecting said dampening assembly with said frame, said spring assembly comprising a shaft extending from said dampening assembly through an aperture in said frame and a spring encasing said shaft and extending from an adjustable nut thereon to the wall of said frame in the vicinity of said aperture.

9. A ski binding comprising a frame attachable to a ski, a dampening assembly attached to said frame, and constituted by two realtively displaceable members, a spring interconnecting said relatively displaceable members of said dampening assembly, and means attached to said dampening assembly for engaging a ski boot mounted upon said ski, whereby a thrust applied to the engaging means results in dampened compression of said spring, wherein said dampening assembly comprises a housing with a base connected to said frame and a top receiving said engaging means therethrough, a piston interiorly of said housing and responsive to said engaging means, a fluid occupying the interior of said housing, and said spring comprises an internal spring extending from said piston to the base of said housing.

10. Apparatus as defined in claim 9 wherein said piston has an orifice therethrough and further including a flanged cup of flexible material overlying said piston, extending to the interior walls of said housing and opening in the direction of said base, whereby a thrust applied to said piston forces said fluid through said orifice and the release of said thrust results in a rapid return of fluid forced through said orifice around the edges of said flanged cup.

11. Apparatus as defined in claim 9 wherein said piston is proportioned to provide a preassigned clearance between it and the interior walls of said housing, and said piston includes a ball-check valve which is closed during a compressional thrust applied to said piston and open when said thrust is removed.

12. Apparatus as defined in claim 9 wherein the materials of said housing and said piston have different coeflicients of expansion, said housing and said piston contracting by ditferent amounts with a reduction in temperature to compensate for a corresponding increase in the viscosity of said fluid.

No references cited.

BENJAMIN HERSH, Primary Examiner I. A. PEKAR, Assistant Examiner 

